Travelling in Colombia (Bogotá)

Dear all,
It's a long time that I've in mind to discover Colombia. A friend of mine and I might visit the country end of June - beginning of July. We don't intend to travel via a travel agency but on our own.
I would like to know if it's globally safe for two girls to travel around and if yes, which regions we should better avoid. Also, since we both love trekking and I heard that Colombia has some beautiful national parks, would this be an option or should we better avoid it? Million thanks for your help!
Have a great day and hope to have the pleasure of meeting you at Internations Bogota in case we go to Colombia!
Valerie